Do biofuels massively worsen water stress?

droughtDoes bioenergy place such massive pressure on water resources that it zeroes out the climate change benefits? Tweets around a recent article from PNAS say “yes, that’s so!”

But is it really so? 

The dire headline tweeted by Carbon Brief — “Heavy reliance on bioenergy could mean a 42% increase in water consumption across the US by 2100” — suggested that here was a cautionary tale on water use that would be of great interest to the biotechnology community. Indeed, the tweet takes us, via this Carbon Brief article, to an underlying article in the July Proceedings of the National Academy of Sciences.

The article inspired Peter Gleick (of the Pacific Institute) to tweet “There is smart climate mitigation and stupid climate mitigation. Using biofuels massively worsens water stress.” Gleick added, in an interview with Carbon Brief:

“The stupid ones are those that reduce emissions of greenhouse gases, but make other problems worse. In this case, attempting to mitigate greenhouse gas emissions by replacing fossil fuels with biofuels falls into [this] category – something people have argued for a long time – precisely because of the massive pressure biofuels place on water resources.”

Well, does it? Does using biofuels massively worsen water stress?


Looking at the hard data

The scenario offered by the article is, in turn, based on a climate change mitigation scheme originally published in 2011 in Climate Change. There, the authors considered a situation in which 178 exajoules of bioenergy would be consumed in 2100, as part of an overall model of where the world will get its energy by that time.

Now, let’s put that amount of energy usage in context. The United States in 2012 consumed 90 exajoules of energy. Total. All sources, all uses. The whole enchilada.

So, 178 exajoules — twice what you need to power the entire United States — is a very intensive use case.

Can we benchmark this? How many exajoules of bioenergy are produced in the US today? Bioenergy represents around 7 percent of overall fuel BTUs and roughly 1.5 percent of the power mix. Overall, around 3.1 exajoules.

So, if the world were to use 178 exajoules of bioenergy, how many would be produced here to create that massively worsened water stress? Based on the US having a 12-20% share of energy demand by 2011, the scenario contemplates a growth of bioenergy to 21-36 exajoules.

How much is that, please? If every car in America drove every mile on bioenergy, that would be roughly 26 exajoules. Every vehicle, every drop.

Crazy things happen in crazy scenarios

When pigs fly, there’s going to be pig manure everywhere, in your pool, on your picnic table, on your children’s innocent little heads. Should we ban pigs?

Which of course brings up the old scientific saying I just made up, “before you tweet the unbearable consequences, do a reality check on the unreachable assumptions”.

Some notes on this particular study

One, the entire change in energy crop use was modeled around the use of a single crop, switchgrass. Which simplifies the research workload. Yet, it’s kinda like modeling the future of the world based on every person living on a strict diet of turnips.

Two, the underlying scenario in Climate Change made no allowance for technological improvements in water inputs. That’s 85 years from now. 85 years ago — that was like the Dark Ages. 85 years ago, my grandfather, and probably yours too, didn’t have running water at all. 85 years is forever in the world of high tech.

So think of it this way:

Assumption of bioenergy growth modeled in this article, expressed as a percentage: 700-1000

Most optimistic-case industry expectations of growth, expressed as a percentage: 300

Article’s assumptions of improvement in water intensity over the next 85 years, as a percentage: 0

Percentage of Silicon Valley’s 246 agricultural technology company investments in 2014 focused on “Precision Ag”, or the micro-analytic systems related to managing inputs: 30

You don’t need to take a shorter shower

Rest easy, climate friends. The US water supply is not in peril.  You won’t need to take a shorter shower, or deny a glass of water to a thirsty child, because of the rise of the advanced bioeconomy. You have been hobgoblin’d by people using scare tactics to draw attention to issues they care about. Don’t hate them for their excessive zeal: water’s worth caring about.

But, in this case, the impact on your shower will be…better performing soaps and shampoos. And more sustainable fuels to power your trip to and from the store.

Bioenergy is a good, solid niche strategy in a world that needs it, along with solar, wind, hydro, electric vehicles, hydrogen cars, and continuing use of (though in a dwindling percentage) fossil fuels.  To the extent that it uses waste, the use of water is negligible; in some cases, the process produces net water. With energy crops, these will be produced generally in areas with sufficient rainfall — in the future, they’ll be continuously improved in terms of water needs, and agriculture itself will improve via the field known as AgTech. In fact, it already is.

The Revolution in AgTech – The 8-Slide Guide

Interested in the convergence between genetics, robotics, mobile tech, and cloud computing? That’s the world of AgTech — and there were 264 Silicon Valley invested-companies last year alone. Here’s our 8-Slide Guide.

The Bottom Line

Bioenergy investment and deployment doesn’t happen in a vacuum — it proceeds along with improvements in crop productivity and inputs, waste aggregation, infrastructure deployment, and application development for novel molecules. Water input R&D is important — not just for bioenergy — but for every use of water.

The only path forward are sustainable biofuels — and sustainable biofuels don’t cause dire water effects.

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